// SPDX-License-Identifier: GPL-2.0-only
/*
 * Toggles a GPIO pin to power down a device
 *
 * Jamie Lentin <jm@lentin.co.uk>
 * Andrew Lunn <andrew@lunn.ch>
 *
 * Copyright (C) 2012 Jamie Lentin
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/gpio/consumer.h>
#include <linux/of_platform.h>
#include <linux/module.h>

#define DEFAULT_TIMEOUT_MS 3000
/*
 * Hold configuration here, cannot be more than one instance of the driver
 * since pm_power_off itself is global.
 */
static struct gpio_desc *reset_gpio;
static u32 timeout = DEFAULT_TIMEOUT_MS;
static u32 active_delay = 100;
static u32 inactive_delay = 100;

static void gpio_poweroff_do_poweroff(void)
{
    BUG_ON(!reset_gpio);

    /* drive it active, also inactive->active edge */
    gpiod_direction_output(reset_gpio, 1);
    mdelay(active_delay);

    /* drive inactive, also active->inactive edge */
    gpiod_set_value_cansleep(reset_gpio, 0);
    mdelay(inactive_delay);

    /* drive it active, also inactive->active edge */
    gpiod_set_value_cansleep(reset_gpio, 1);

    /* give it some time */
    mdelay(timeout);

    WARN_ON(1);
}

static int gpio_poweroff_probe(struct platform_device *pdev)
{
    bool input = false;
    enum gpiod_flags flags;

    /* If a pm_power_off function has already been added, leave it alone */
    if (pm_power_off != NULL) {
        dev_err(&pdev->dev, "%s: pm_power_off function already registered\n", __func__);
        return -EBUSY;
    }

    input = device_property_read_bool(&pdev->dev, "input");
    if (input) {
        flags = GPIOD_IN;
    } else {
        flags = GPIOD_OUT_LOW;
    }

    device_property_read_u32(&pdev->dev, "active-delay-ms", &active_delay);
    device_property_read_u32(&pdev->dev, "inactive-delay-ms", &inactive_delay);
    device_property_read_u32(&pdev->dev, "timeout-ms", &timeout);

    reset_gpio = devm_gpiod_get(&pdev->dev, NULL, flags);
    if (IS_ERR(reset_gpio)) {
        return PTR_ERR(reset_gpio);
    }

    pm_power_off = &gpio_poweroff_do_poweroff;
    return 0;
}

static int gpio_poweroff_remove(struct platform_device *pdev)
{
    if (pm_power_off == &gpio_poweroff_do_poweroff) {
        pm_power_off = NULL;
    }

    return 0;
}

static const struct of_device_id of_gpio_poweroff_match[] = {
    {
        .compatible = "gpio-poweroff",
    },
    {},
};

static struct platform_driver gpio_poweroff_driver = {
    .probe = gpio_poweroff_probe,
    .remove = gpio_poweroff_remove,
    .driver =
        {
            .name = "poweroff-gpio",
            .of_match_table = of_gpio_poweroff_match,
        },
};

module_platform_driver(gpio_poweroff_driver);

MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>");
MODULE_DESCRIPTION("GPIO poweroff driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:poweroff-gpio");
